Of triumph and tragedy

The last week has seen some momentous and tragic events occur in the annals of space flight and space exploration, with tragedy leading the way following the break-up of Virgin Galactic’s SpaceShipTwo vehicle on Friday, October 31st, resulting in the death of co-pilot Michael Alsbury and the serious injury of pilot Peter Siebold.

The loss of SpaceShipTwo came just a few days after an Antares booster, operated by Orbital Sciences and which should have been launching an unmanned Cygnus resupply vehicle to the International Space Station (ISS), was ordered to self-destruct seconds after lifting off of the pad.

Understandably overshadowed by the loss of SpaceShipTwo was the news that China has enjoyed a further success as a part of its ambitious lunar mission plans, and NASA has achieved a further “first” on Mars with Curiosity.

The news from Curiosity came after what has been another period of relative quiet from the MSL team following the successful gathering of a rock sample from a drilling operation into a target rock outcrop dubbed “Confidence Hills” within the “Pahrump Hills” region at the base of “Mount Sharp”.

Since that time, Curiosity has been on something of a “walkabout”, as NASA JPL is calling it (“roll around” probably doesn’t give the right impression…) within the “Pahrump Hills” area whilst simultaneously analysing the samples gathered from “Confidence Hills” at the end of September, and also keeping an eye out for passing comets.

Curiosity’s “walkabout” in the “Pahrump Hills” at the base of “Mount Sharp” in October 2014. The route starts at “Confidence Hills”, the site of a successful drilling operation, and winds up to “Whale Rock”. Red dots indicate points at which the rover paused overnight, white dots denote points at which it stopped to gather images and data, perhaps over several days

As well as the familiar aboriginal reference, “walkabout” is also a term used by field geologists to describe walking across a rocky outcrop in order to determine the best places from which to examine it – which is precisely what Curiosity was ordered to do through October.

During the walkabout, Curiosity made a number of stops for data and image gathering, before arriving at a point dubbed “Whale Rock”, just below another high point which appears to mark the point at which “Pahrump Hills” join the “Murray formation”, the next destination for the rover once studies of “Pahrump Hills” has been completed. The rover will remain parked at “Whale Rock” as the science team analyses the images and data gathered in order to determine where the rover should return to carry out more detailed investigations.

The material obtained from the “Confidence Hills” drilling operation contained in the rover’s sample scoop after being sifted and graduated by the CHIMRA device in the rover’s robot arm turret, and about to be delivered to the input ports ready for analysis by the instruments in the rover’s body. This image was taken by Curiosity’s Mastcam, and has been white-balanced so that lighting conditions match daytime light on Earth

In the meantime, and in the “first” mentioned above, Curiosity has confirmed that the samples gathered from “Confidence Hills” contain mineral deposits what had been mapped from orbit. The mineral in question in Hematite – which has been found elsewhere on Mars by both of the MER rovers, Opportunity, and the now defunct Spirit.

However, the significance of the “Confidence Hills” analysis, carried out by the rover’s on-board Chemistry and Mineralogy (ChemMin) instrument, confirms predictions made from the analysis of data returned by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter that Hematite deposits would exist within the rocks of the mountain’s lower slopes. This confirmation gives the science team greater confidence that the analysis of orbital data can help them make even better choices of while the rover should carry out drilling operations etc. It also means that the rover’s on-the-spot analysis and observations can be set directly into the broader geologic history of “Mount Sharp” as obtained by orbital data.

Curiosity may spend weeks or months at Pahrump Hills before proceeding farther up into the “Murray formation” and on to “Hematite Ridge”, a further location of interest to scientists. The mineral is of particular interest to scientists not so much because it might be indicative of a water-rich history in the region (as was the case with the discoveries made by Opportunity and Spirit) – Gale Crater has already more than yielded enough evidence of wet conditions being prevalent in its past history. Rather, the hematite on and in “Mount Sharp” helps scientists further understand oxidation conditions within the region.

China Returns from a trip around the Moon

It might still be relatively young, but China’s space programme has set itself some ambitious goals, having already embarked on a programme to develop an oribiting space station by the 2020s, with the Tiangong 1 (“Heavenly Palace”) module currently in orbit, and its replacement, Tiangong 2, due to be launched in 2016, with work commencing on the multi-module Tiangong 3 station starting in 2018. Alongside of this, China is contemplating human missions to the Moon, possibly starting in 2024/5.

As a precursor to the latter, the Chinese landed a small lunar rover called Yutu (“Jade Rabbit”) on the Moon at the end of 2013, which managed to trundle around for 42 days before its drive mechanism seized. Now they have gone a stage further with a mission to fly a robot vehicle around the Moon and back.

A remarkable view of the Moon with Earth beyond, as taken by China’s Chang’e 5 lunar return test vehicle in late October 2014. Image via CCTV News

This 8-day mission came to a close on Saturday, November 2nd, when the Chang’e-5 T1 test capsule, nicknamed Xiaofei (pronounced “Sophie”) successfully soft-landed in Inner Mongolia following an 8-day flight out around the Moon and back.

While the vehicle did not enter lunar orbit, the mission is seen as an important step in China’s lunar ambitions, being the precursor of a 2017 mission to land a vehicle on the Moon to gather rock and soil (regolith) samples and then return them to Earth for study. This mission is in turn seen as a precursor to the planned human missions to the Moon.

Antares Booster Malfunction

The first Cygnus resupply vehicle approach the space station in 2013. Image: NASA

Antares is a private launch vehicle built and operated by Orbital Sciences Inc., who alongside SpaceX, have a contract to fly resupply missions to the International Space Station. In this capacity, the Antares is used to launch Orbital Science’s Cygnus vehicle, capable of delivering around 2 tonnes of payload to the ISS.

On October 28th, the third Antares / Cygnus mission to the ISS suffered a catastrophic loss 14 seconds into the flight, after an apparent turbo-pump malfunction in at least one of the booster’s main engines caused an explosion which crippled the vehicle, resulting it in starting to fall back towards the launch pad. To prevent the vehicle impacting the launch complex, Range Safety Officers at the Mid-Atlantic Regional Spaceport, a commercial space launch facility in the state of Virginia, USA, issued the command for the vehicle to self-destruct. As a result, while the vehicle and payload were destroyed, the launch pad suffered “minimal” damage. No-one was injured or killed in the accident.

SpaceShipTwo

Sadly, the same cannot be said for the loss of Virgin Galactic’s SpaceShipTwo. Designed to lift up to six passengers on a sub-orbital flight to experience several minutes of free-fall, SpaceShipTwo sits at the heart of Virgin Galactic’s space ambitions, and has been undergoing tests in the skies above California’s Mojave Desert for the past several years.

On Friday, October 31st, as a part of this test programme, the first SpaceShipTwo vehicle, called VSS Enterprise, was carried aloft by its launcher vehicle, White Knight Two, for what should have been the first flight test of a new version of the vehicle’s rocket motor, which had been completely redesigned after a 2007 static ground test of one of the original motors resulted in an explosion and three fatalities.

SpaceShipTwo suspended under the wing of the White Knight Two “mothership” in February 2012, ready for unpowered subsonic test flights (image courtesy of Mark Greenberg, Virgin Galactic

However, shortly after SpaceShipTwo detached from its mothership and the rocket engine was fired, it broke-up in mid-air, killing co-pilot Michael Alsbury and seriously injuring pilot peter Siebold, who managed to somehow survive the vehicle’s disintegration and parachute to Earth.

Immediately following the accident, fingers were immediately pointed at the use of nitrous-oxide as the motor’s oxidizer, with numerous “I told you so” comments in the media. However, according to preliminary investigations by the US National Transportation Safety Board (NTSB), neither the rocket motor nor its fuel systems appear to have contributed to the accident. Attention instead is focused on the vehicle’s re-entry “feathering system”.

Because the vehicle’s velocity is much lower than that required to reach orbit, it doesn’t require high-tech re-entry systems. Instead, the vehicle’s two tail booms, together with a section of the wing surfaces are “flipped up” to an angle of 65-degrees, and act something like a badminton shuttlecock, allowing the vehicle to drop gently back into the denser atmosphere, rather than trying to punch its way through like a flying brick. Once the vehicle reaches an altitude where aerodynamic life works, the tail booms swing back down, and SpaceShipTwo glides to a landing.

SpaceShipTwo in full “feathered” mode during an unpowered drop test in May, 2011 as a part of testing the feathering system, which saw the booms deployed to their full “feather” position of 65 degrees for 1 minute 15 seconds before being reset to “glide” mode. Image via Clay Centre Observatory/Virgin Galactic

Under normal operations, this “feathering system” requires the flight crew to adjust two separate levers in the cockpit. The first unlocks the tail booms from their horizon position, the second causes them to flip up. Neither lever is supposed to be activated while the vehicle is under powered flight. Nevertheless, according to the NTSB, video footage transmitted from the cockpit shows co-pilot Michael Alsbury unlocking the feathering system just nine seconds after the vehicle’s rocket motor had ignited. Two seconds after later, the tail booms deployed to their feathered configuration, and SpaceShipTwo suffered a catastrophic break-up in mid-air.

The NTSB has emphasised that the discovery that the tail booms had been unlocked is not necessarily a statement of the overall cause of the accident, although it would appear to have been a contributing factor. Significantly, the lever required to actually flip the tail booms to the “feathered” position was never activated, so even while “unlocked” the booms should not have deployed.

Investigations into the accident are liable to take several months, and will involve all aspects of Virgin Galactic’s operations, and not just the design of the vehicle itself. Commenting on the NTSB’s work, chairman Christopher Hart said, “”We’ll be looking at training issues. We’ll be looking at ‘was there pressure to continue testing?’ We’ll be looking at safety culture. We’ll be looking at the design, the procedures—we’ve got many, many issues to look into much more extensively before we can determine the cause.”

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